Nearly 60% of European wetlands have been lost to drainage or to the cessation of grassland management. Large amounts of resources are put into wetland restoration with the aim to recover ...biodiversity. However, few studies have simultaneously evaluated effects of management, wetness and flooding dynamics on biodiversity of restored wetlands such as seasonally flooded wet grasslands. We inventoried bird communities over 4 years at 137 sites (each 3·1 ha) within five restored wet grassland areas in Sweden to investigate whether species richness and occurrence of 12 common wet grassland species were related to (i) local conditions such as management (grazing, mowing and unmanaged areas), basic wetness and spring flooding dynamics. Further, we investigated whether (ii) the composition of the adjacent landscape (20 ha) related to local bird diversity and (iii) species turnover (i.e. beta diversity) differed between sites characterized by their basic wetness, degree of flooding and predominant management regime. Local species richness was positively linked to degree of flooding and basic wetness of grasslands but not to type of grassland management. Species richness tended also to be negatively linked to proportion of forest at the landscape scale. Although variable, the same results were also true concerning the probability of the occurrence of a single species at the local scale. Species turnover between sites, and thus total species richness, was distinctly higher in (i) grazed as compared to mowed grasslands except in dry non‐flooded grasslands and (ii) flooded as compared to non‐flooded sites. Similar patterns held for the subset of 12 red‐listed species. We suggest that the high beta diversity in grazed and flooded grasslands is driven by the heterogeneous vegetation structure, resulting in good conditions for foraging and nesting for several wet grassland bird species. Synthesis and applications. The selection of wetlands for conserving wet grassland birds should prioritize temporary flooded grasslands of moderate wetness, preferably far from forest edges. Restoration and management of wet grasslands should include water level management, removal of shrubs and trees, and low‐intensity grazing, whereas mowing could be used in non‐flooded grasslands of low basic wetness.
The Arctic is experiencing rapidly warming conditions, increasing predator abundance, and diminishing population cycles of keystone species such as lemmings. However, it is still not known how many ...Arctic animals will respond to a changing climate with altered trophic interactions. We studied clutch size, incubation duration and nest survival of 17 taxa of Arctic‐breeding shorebirds at 16 field sites over 7 years. We predicted that physiological benefits of higher temperatures and earlier snowmelt would increase reproductive effort and nest survival, and we expected increasing predator abundance and decreasing abundance of alternative prey (arvicoline rodents) to have a negative effect on reproduction. Although we observed wide ranges of conditions during our study, we found no effects of covariates on reproductive traits in 12 of 17 taxa. In the remaining taxa, most relationships agreed with our predictions. Earlier snowmelt increased the probability of laying a full clutch from 0.61 to 0.91 for Western Sandpipers, and shortened incubation by 1.42 days for arcticola Dunlin and 0.77 days for Red Phalaropes. Higher temperatures increased the probability of a full clutch from 0.60 to 0.93 for Western Sandpipers and from 0.76 to 0.97 for Red‐necked Phalaropes, and increased daily nest survival rates from 0.9634 to 0.9890 for Semipalmated Sandpipers and 0.9546 to 0.9880 for Western Sandpipers. Higher abundance of predators (foxes) reduced daily nest survival rates only in Western Sandpipers (0.9821–0.9031). In contrast to our predictions, the probability of a full clutch was lowest (0.83) for Semipalmated Sandpipers at moderate abundance of alternative prey, rather than low abundance (0.90). Our findings suggest that in the short‐term, climate warming may have neutral or positive effects on the nesting cycle of most Arctic‐breeding shorebirds.
Conservation status and management priorities are often informed by population trends. Trend estimates can be derived from population surveys or models, but both methods are associated with sources ...of uncertainty. Many Arctic-breeding shorebirds are thought to be declining based on migration and/or overwintering population surveys, but data are lacking to estimate the trends of some shorebird species. In addition, for most species, little is known about the stage(s) at which population bottlenecks occur, such as breeding vs. nonbreeding periods. We used previously published and unpublished estimates of vital rates to develop the first large-scale population models for 6 species of Arctic-breeding shorebirds in North America, including separate estimates for 3 subspecies of Dunlin. We used the models to estimate population trends and identify life stages at which population growth may be limited. Our model for the arcticola subspecies of Dunlin agreed with previously published information that the subspecies is severely declining. Our results also linked the decline to the subspecies' low annual adult survival rate, thus potentially implicating factors during the nonbreeding period in the East Asian–Australasian Flyway. However, our trend estimates for all species showed high uncertainty, highlighting the need for more accurate and precise estimates of vital rates. Of the vital rates, annual adult survival had the strongest influence on population trend in all taxa. Improving the accuracy, precision, and spatial and temporal coverage of estimates of vital rates, especially annual adult survival, would improve demographic model-based estimates of population trends and help direct management to regions or seasons where birds are subject to higher mortality. LAY SUMMARY Documenting population trends is essential for evaluating the conservation status of wild species such as Arctic-breeding shorebirds. Trends can be estimated with population surveys or by predicting population growth based on survival rates and fecundity, but both methods are challenging, especially for species with large or remote geographic distributions. We used recent broad-scale estimates of survival and fecundity to develop population models for 6 species of Arctic-breeding shorebirds. The arcticola subspecies of Dunlin is likely in severe decline, but our trend estimates for all species showed high uncertainty. Uncertainty around the values of annual adult survival rates was a key driver of the uncertainty around the trend estimates. Our work highlights the need for better estimates of annual adult survival, seasonal survival, juvenile survival, and breeding propensity for these Arctic-breeding shorebirds.
Identifying animals as sentinels for humans and other animal species is an excellent method for understanding exposure to environmental contamination at different times and places. Shorebirds are ...useful sentinels because they have a world-wide distribution, eat a range of prey, and are eaten by a range of other species, including humans. We collected blood from semipalmated sandpipers (Calidris pusilla) wintering in northern (Suriname N = 71) and northeastern (Brazil N = 61) South America to examine levels of heavy metals and metalloids (arsenic, selenium), and compare them to blood levels in sandpipers at a heavily used stopover site in New Jersey (N = 30; Delaware Bay, NJ). Since blood represents relatively recent exposure, it can provide information on where and when the birds were exposed. Levels were highest in Brazil for arsenic and particularly selenium; highest in Suriname for cadmium and lead; and highest in New Jersey for chromium. Samples from Brazil and Suriname presented higher levels of mercury than did those from New Jersey. There were no geographic differences for cobalt. Levels of all metals were generally within an order of magnitude. The significant geographic difference for selenium was interesting because it is regulated in the body. Selenium levels in the NJ sample were directly proportional to levels found in their principle food at this migration stopover site (eggs of horseshoe crab, Limulus polyphemus). Mean selenium level was almost an order of magnitude higher in the semipalmated sandpiper blood samples from Brazil (mean of 27,500 µg/L= ppb) compared to the other sampling locations (mean > 5330 µg/L). This is a toxic level and cause for concern and further investigation, alerting us to look for other evidence of excess selenium exposure. Otherwise the levels of other metals are generally not high enough to cause harm to the sandpipers themselves or to predators that eat them. We discuss the implications for these birds and their exposure to contaminants at different stopover sites.
•Shorebirds are useful sentinels because of their worldwide distribution.•Metals levels were examined in sandpiper blood from Brazil, Suriname and New Jersey.•Mercury levels were lowest in New Jersey compared to the other sites.•Selenium levels were higher in Brazil (order of magnitude higher) than the other sites.•Except for selenium, levels were below any known toxic levels for birds.
1.Following targeted conservation actions most goose populations have increased. The growing goose populations caused an increase in human-wildlife conflicts and have the potential to affect nature ...values. As meadow birds, including meadow-breeding waders, were declining throughout Western Europe, the possible negative effect of rising numbers of foraging barnacle geese on their breeding success has been questioned.2.We used GPS-transmitter data to measure the density of foraging barnacle geese during daylight hours. Using dynamic Brownian Bridge Movement Models (dBBMM), we investigated the effect of barnacle goose density on the territory distribution of five wader species, and on nest success of the locally common Northern lapwing. We used model selection methods to identify the importance of barnacle goose density related to other environmental factors.3.Our results showed an insignificant positive association between barnacle goose density and nest territory density of the Northern lapwing and common redshank. Barnacle goose density had no influence on territory selection of godwit, oystercatcher and ringed plover. We did, however, find a negative correlation between barnacle geese density and the nest success of the Northern Lapwing.4.We infer that either barnacle goose foraging leads to improved territory conditions for some wader species, or that both barnacle geese and waders prefer the same type of habitat for foraging and nesting. Higher barnacle goose density was correlated with fewer Northern lapwing nests being successful.5.Synthesis and application: Experimental research is needed to disentangle the causal chain, but based on our observational findings, we suggest to increase water logging that may attract both barnacle geese and wader species. Further investigation on the effects of barnacle geese on wader species is necessary to identify the cause of the negative correlation between barnacle geese density and nest success of lapwings; nest protection experiments could give further insight.
We review the conservation issues facing migratory shorebird populations that breed in temperate regions and use wetlands in the non‐breeding season. Shorebirds are excellent model organisms for ...understanding ecological, behavioural and evolutionary processes and are often used as indicators of wetland health. A global team of experienced shorebird researchers identified 45 issues facing these shorebird populations, and divided them into three categories (natural, current anthropogenic and future issues). The natural issues included megatsunamis, volcanoes and regional climate changes, while current anthropogenic threats encompassed agricultural intensification, conversion of tidal flats and coastal wetlands by human infrastructure developments and eutrophication of coastal systems. Possible future threats to shorebirds include microplastics, new means of recreation and infectious diseases. We suggest that this review process be broadened to other taxa to aid the identification and ranking of current and future conservation actions.
Agricultural intensification has affected wildlife across Europe, triggering steep declines and regional extinctions of farmland birds. Effective conservation activities are essential for the ...preservation of biodiversity in an agricultural landscape, but current efforts have not succeeded in halting these declines. Here we investigate a ground-nesting shorebird, the collared pratincole Glareola pratincola, which has shifted its habitat use in Central Europe over the last 20 years from alkaline grasslands to intensively managed agricultural fields. We show that nesting success was different between three agricultural habitat types, with the highest nesting success in fallow lands and the lowest in row crops. Nesting success was also associated with the timing of breeding and breeding density, as nests produced early in the breeding season and those in high-breeding-density areas hatched more successfully than those produced later in the season and at low density. We implemented direct conservation measures including marking nests and negotiating with farmers to avoid cultivating the field between nest markers, controlling nest predators and, most recently, creating suitable nesting sites and foraging areas for pratincoles. As a result of these conservation actions, nest survival increased from 11.2% to 83.5% and the size of the breeding population increased from 13 to 56 pairs during 2012–2021. Thus, we show that agricultural landscapes can continue to provide suitable habitats, and targeted conservation actions have the potential to reverse the declines of farmland species.
The Great Knot is a species from the Scolopacidae family of waders migrating within the East Asian-Australasian Flyway, and studies on this species have contributed greatly to understanding of ...migration ecophysiology and migration strategies in long-distance migrants. In this paper, we provide the first description of biometric variability and sexual size dimorphism in Great Knots. During the study on the Kamchatka Peninsula, 683 adults and 229 juveniles were measured and sexed molecularly. In adults, the mean measurements of females were larger than in males, except for tarsus length. In juveniles, at the early stage of migration from breeding to wintering grounds, apparently growth was not complete. Sexual dimorphism was small, with only wing length being significantly longer in females than in males. All dimensions of juveniles were smaller than those of adults, especially in bill length. The most sexually dimorphic trait in both adults and juveniles was wing length, and the most effective discriminant function with wing length as a single predictor correctly identified the sex of 76% of birds in both age classes. However, molecular sexing is the method of choice for reliable sexing, especially in juveniles.
The distributions of eight out of nine common species of waders (Charadrii) overwintering on UK estuaries have changed in association with recent climate change. These birds represent a high ...proportion of various populations from breeding grounds as far apart as Greenland to the west to high‐arctic Russia to the east. During warmer winters, smaller proportions of seven species wintered in south‐west Britain. The distributions of the smaller species show the greatest temperature dependence. The opposite was found for the largest species and no relationship was found for a particularly site‐faithful species.
In north‐west Europe, the winter isotherms have a broadly north to south alignment, with the east being colder than the west. The average minimum winter temperatures across the UK having increased by about 1.5°C since the mid‐1980s, the temperatures on the east coast during recent winters have been similar to those of the west coast during the mid‐1980s. On average, estuaries on the east and south coasts of Britain have muddier sediments than those on the west coast and thus support a higher biomass of the invertebrate prey of waders. We suggest that, with global climatic change, the advantage gained by waders wintering in the milder west to avoid cold weather‐induced mortality is diminished. Consequently, more choose to winter in the east and thus benefit from better foraging opportunities. The implications of these results are considered in terms of a site‐based approach to wildlife protection used in Europe and elsewhere.
The relative fitness of individuals across a population can shape distributions and drive population growth rates. Migratory species often winter over large geographic ranges, and individuals in ...different locations experience very different environmental conditions, including different migration costs, which can potentially create fitness inequalities. Here we used energetics models to quantify the trade-offs experienced by a migratory shorebird species at locations throughout the nonbreeding range, and the associated consequences for migratory performance, survival, and breeding habitat quality. Individuals experiencing more favorable winter conditions had higher survival rates, arrived on the breeding grounds earlier, and occupied better quality breeding areas, even when migration costs are substantially higher, than individuals from locations where the energy balance on the wintering grounds was less favorable. The energy costs and benefits of occupying different winter locations can therefore create fitness inequalities which can shape the distribution and population-wide demography of migratory species.
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